Doctor



J. A. LAFORE Feb. 16, 1932.

DOCTOR IN VE TOR.

Filed June 15, 1950 Md-Qqf ATTORNEY I Patented pt. 16, 1932 UNITED STATES PATENT OFFICE JOHN A. LAFORE, OI LOWER MERION TOWNS HIP, MONTGOMERY COUNTY, PENNSYLVANIA DOCTOR Application filed June 13,

My invention relates to scrapers, more commonly called doctors, for removing from rolls, cylinders, and the like, used in various processes, material undesirably adher ng thereto; and more particularly my inventlon relates to improvements in doctors utilizable in the paper making industry.

In accordance with my inyention, the scraper or doctor blade, preferably slotted or slit from its rear edge toward the front or scraping edge, is mounted in a suitable supporting structure in such wise that the doc- "tor or scraper blade floats, whether or not it be anchored or secured at one point or within a restricted portion of its length, whereby upon expansion, due to temperature rise, particularly where the doctor blade cooperates with a heated cylinder or roll, as in the paper making industry, it may expand freely and thereby prevent warping or disalignment of the scraping edge.

Further in accordance with my invention,

there'may be employed a shield or shields on either or both sides of the doctor blade covering the slits or slots therein to prevent passage of scrapings or other matter on to the material undergoing formation or treatment or on to the rolls or cylinders; further in accordance with my invention, the shieldele- 3o ment or elements may be mounted similarly to the doctor blade itself to permit floating or ready expansion without buckling, or, if desired, may be secured to the support at various intervals throughout its length.

My invention resides in structure of the character hereinafter described and claimed.

For an illustration of some of the various forms my invention may take, reference is to be had to the accompanying drawings, in which:

Fig. 1 is a View in perspective of structure embodying my invention.

Fig. 2 is a section on the line 2-2 of Fig. 1, with the blade, in elevation, related to a cylinder, calender roll or other roll.

Fig. 3 is a plan view of a modification.

Fig. 4 is a fragmentary View on enlarged scale, with a portion of the support .broken away.

1930. Serial No. 460,809.

Fig. 5 is a fragmentary plan view of a further modification.

Fig. 6 is a sectional view on line 6--6 of, Fig. 5.

Fig. 7 is a cross section, in line with a blade slot, showing slot-covering means.

Referring to Figs. 1 and 2, C represents in fragmentary outline a cylinder, roll, or the like, such, for example, as a steam cylinder, a calender or other roll utilized .in the paper making industry. Engaging the periphery of the cylinder is the doctor blade B, of any usual or suitable material, as steel, rustless steel or the like. It is held in a channel or slot in the bracket or support S or in other suitable way, which may be of the usual angular type, or may be an angle iron with a channeled member secured-thereto, having at its opposite ends the usual supporting pins or pivots P.

At any suitable point in its length, the blade B may be anchored or secured to the support S, as by a bolt 6, or by a rivet or any equivalent means. In the example illustrated by Fig. 1, the anchorage is substantially at the middle of the longitudinal extent of the blade B. The anchorage may, however, be at either end or at any other suitable point throughout the length of the blade; and several rivets or bolts b may fixedly hold the blade to the support provided they be within only a small portion of the length of the blade such that expansion thereof within that short range is insubstantial.

In consequence the blade is floatingly or loosely mounted in the slot 5- in the support S. and is throughout its length free to expand, without crimping, warping, buckling, or other deformation, or disalignment of the front or cylinder engaging edge e, which otherwise occurs when the blade is held or secured at a plurality of points throughout its length and when subjected to temperature changes, and more particularly to tem perature rise, when contacting or engaging a rollor cylinder C which is at elevated tein perature, as occurs for example, in paper making and other processes.

By a floating structure of this character, the blade B may freely expand or contract, 1'

without restriction, under the influence of temperature changes, and maintain its edge e throughout its length in desired and perfect operative alignment and relation to the cylinder or roll C. The floating mounting of the blade B permits also its expansion or contraction relatively to its support or bracket S which may and generally does have a different coeificient of thermal expansion. In any event, the floating characteristic is desirable even in case the coetlicient of expansion of the bracket Sis the same as that of the blade B, for in general, the support or bracket S may or will attain a temperature different from and generally lower than that of the blade B. In prior practice, where the doctor blade is tightly secured to the support or bracket at a plurality ofpoints in its length, there will arise, with rising temperature, a tendency to buckle between the anchorages, rendering the blade less effective in scraping or cleaning or otherwise acting upon the surface of the cylinder or roll C.

As indicated, the blade B may have extending from its rear edge f, toward but falling short of its front edge e, the slits or slots a, imparting greater flexibility-to the blade B as a whole and permitting its rear edge to expand and contract freely with its front edge. In my structure, these slots extend as stated to the rear edge 7 where the blade B is entirely free of any other structure, strip or element secured thereto and constituting a component of the blade structure. The blade, when provided with the slots 0;, comprises the forward continuous portion with rearwardly extending integral tongues with free rear edges; and, when employed, the rivets, bolts or equivalent means 6 extend through one or more of the tongues, in the relations and for the purposes described.

While the anchorage b has been described as securing the blade B thereatin fixed position with respect to the support or bracket S, the floating characteristic of the blade may be even further increased as by providing in the blade B a longitudinal slot 0, Fig. 4, in which the rivet or bolt 6 loosely fits, whereby the blade is at no point fixed to the support or bracket S, though it is nevertheless loosely held against too great displacement endwise,

. fixedlyanchored by convenient point, as approximate its middle,

or against working out port S.

As indicated in Fig. 2 the blade B may be the bolt or rivet b at any of or from the supor elsewhere, and at one or more intervals may be provided slots 0, as in Fig. 4, through which loosely extend bolts or rivets such as b, at. In this case, the slots 0 and the bolts or rivets extending therethrough simply loosely hold or guide the blade B, which is nevertheless floating, and free to expand or contract without buckling, warping or other deformation, It will be understood also that even the fixed anchorage 5 of Fig. 3 may be omitted,-asin the case of Fig. l or at the rivet or bolt 6, Fig. 8, the blade B may have a further slot 0; and in either case the blade again floats, in these instances however, without fixation. at any point to the bracket S.

Here again, in Fig. 3, and as preferred, the blade B may have the slits or slots a, produced by saw or any other suitable cutter or instrument.

In Figs. 5 and G, the blade B is again of the floating type, free of fixation at any point to the support S. At each end the blade is cut away to form a notch g, from which extends to the end of the blade the integral portion It extending behind the bolt, rivet or equivalent member 2', which is disposed in the notch. The bolt or rivet i does not secure the blade B, but serves merely as means for retainin it loosely in the slot 8 of the holder S, permitting it freely to float as above described, but limiting its movements longitudinally and transversely of the bracket S.

There may be utilized with the slotted blade B of the character above described a shield plate or cover j, Fig. 7, covering or overlying the slots a, to prevent material or scrapings passing therethrough and falling on to the paper or other material in process or on to the roll or cylinder. In Fig. 7 a plate or cover j, is shown both above and below the blade B, covering the slots a, and disposed with the blade B within the channel or slot .9 in the bracket S. The shield plates j'are preferably detached from the blade structure itself, which floats as before between the two shield plates j, or between a shield plate, if only one is used, and the opposite wall of the slot 8 in bracket S.

With the doctor blade floatingly mounted as above described, whether or not provided with the slots at the thrust of the blade is imparted throughout its length at its rear edge to the rear end wall of the slot or channel 8 in the bracket S. Where, as heretofore commonly practiced,-the blade is secured at a plurality of points throughout its length, fixedly to the support or bracket, the thrust upon the blade, in a direction. from its forward towards its rear edge, is taken by and applied to the elements which so secure the perature, to maintain with exactitude and nicety the necessary relation to the cylinder or roll.

What I claim is:

1. Doctor structure com rising a doctor blade, and a support there or having a slot extending substantially the entire length of the'blade and in which saidblade is floatingly held in such manner as to provide for movement of the blade in a longitudinal direction.

2. Doctor structure comprising a doctor blade, a support therefor, and means for floatingly holding said blade upon said support comprising means fixedly securing said blade to said support within only a small portion of the length of said blade, whereby said blade may freely change in length.

3. Doctor structure comprising a doctor blade having rearwardly extending integral tongues, and a support for the blade having a channel against Whose rear wall abut the rear ends of said tongues.

4. Doctor structure comprising a doctor blade having rearwardly extending integral tongues, and a support in which the said blade is floatingly held, said support having a wall against which abut the rear ends of said tongues.

5. Doctor structure comprising a doctor blade having rearwardly extending integral tongues, and a support in which said blade is floatingly held, said support having a channel in which said tongues are disposed.

6. Doctor structure comprising a doctor blade having slots extending to the rear edge of the blade, a support having a channel receiving said blade, and means disposed in said channel with said blade for covering said slots therein.

7. Doctor structure comprising a blade having slots extending to the rear edge thereof, a support upon which said blade is float ingly held, and means carried by said support covering the slots in said blade.

8. Doctor structure comprising a doctor blade, a support for said blade, said support having means for fixedly securing the blade thereto at a point intermediate the ends of the blade, and having means-for floatingly holding the blade on either side of said securing means to provide for movement of the blade in a longitudinal direction towards its ends from the said fixed point.

9. Doctor structure comprising a doctor blade. a support therefor extending along and supporting the blade at every point over substantially the entire length of the blade, said support h a ring means for fixedly securing the blade thereto at a point intermediate the ends of the blade. and having means for floatingly holding the blade on each side of said securing means to provide for movement of the blade in a longitudinal direction towards its ends from the said fixed point. v

10. Doctor structure comprising a doctor blade having rearwardly extending tongues, a support in which said tongues are held, the support having means intermediate the ends of the blade for fixedly securing one of said tongues, and having means for floatingly holding the tongues of the blade on either side of said fixed tongue to provide for movement of the blade in a longitudinal direction toward its ends from the said fixed point.

11. Doctor structure comprising a doctor blade having rearwardly extending tongues, a support for the blade having a channel extending lengthwise of the support, the tongues being supported in said channel and abutting against the rear wall of the channel, means for fixedly securing one'of the tongues in approximately the central part of the blade, the support having means for floatingly holding the tongues of the blade on either side of said fixed tongue to provide for movement of the blade in a longitudinal direction towards its ends from said central point JOHN A. LAFORE, 

